Method of making radio speakers



April 8, 1952 B. T.'SETCHELL 2,591,881

7 I 7 METHOD OF MAKING RADIO SPEAKERS v 7 Filed Feb. 28, 1947 4Sheets-Sheet 1 BARTON T. SETC HELL mag April 8, 1952 B. 'r. SETCHELL2,591,881

' YMETHQD OF MAKING RADIO SPEAKERS Filed Feb. 28, 1947 4 Sheets-Sheet 2grwmvbom Z BARTON T. SETcHsu.

' B. T. SQYETCHELLT METHODOF MAKING RADIO SPEAKERS Aim-i1 s; 1952 FiledFeb. 28, 1947 v 4'Shee ts-Sheet 3 F]. E. S

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B. T. SETCHELL METHOD OF MAKING RADIO SPEAKERS April 8, 1952 4Sheets-Sheet 4 Filed Feb. 28, 1947 ELLE. .LEI

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speaker pot.

M It is an object of the present vide a means of applying a coat ofadhesive to the "surface of the coil wire during the formation of"partment. .dermic needles on opposite sides of the adhesive--compartment-through which the wire is guided ---duringits entrance toand exit fromthe adhesive Hchambenp Patented Apr. 8, 1952 Barton T.Setchell. St. Paul, Minn. Application February 28, 1947. Serial No.731,579

2 Claims.

My invention relates to an improvement in apparatus for making radiospeakers and the like, wherein it is desired to reduce the'cost ofmanufacture of these articles.

In the manufacture of radio speakers, it is common practice to employ adiaphragm formed the same. This coil must be positioned and formed withextreme accuracy if the speaker is to operate properly in view of thefact that the coil 29-15557) r j .i

An added feature of the present invention. resides in the provision of arotatable spindleon which the speaker diaphragm may be mounted offibrous material and to secure to this dia phragm a paper core having awire coil encircling must be received in a narrow circular gap between Ithe polepiece and an encircling aperture in the Considerable difficultyis experienced in properly forming these coils and in properlypositioning the coils on the speaker diav phragm. p

invention to prothe coil. In the past it has beenu'sual practice 7 toapply a coating of adhesive to the ring shaped paper core on whichthecoil is wound, to Wind during the formation of the paper core; .Thisspindle is provided with a core about which :the paper sleeve supportingthe coil maybe wrapped. This paper sleeve is wrapped about the mandreland adhered to the surface of. thediaphragmwith a suitable cement. Meansare'provided for regulating the length of the coil wrappedthereabout sothat the desired number of turns is provided on the'coil. l

A further feature of the present invention lies in the provision of amovable adhesive chamber through which the wire is drawn before it; is

wrapped aboutfthe paper sleeve. The adhesive member is movable so thattheiwiremay follow 3'. substantially straight path while travellingfromthe source of supply into. winding position.

One of the primary difficulties experienced in the coil on'this core,and to apply a second coat of adhesive over the surface of the coil. Byapplying the adhesive directly to the wire, the

necessity of stopping to apply successive coats of adhesive to the paperand coil is obviated; thus thespeaker pot'to be of minimum width.

'An added feature of the present invention lies in the provision of ameans for automatically apsembly of the speaker.

proper formation of the voice coil and in maintaining this coil inproper shape during thetgas- It ,is usual practice. Ito form the voicecoil over acollapsible'mandrel either with or without its paper coreandg-tojapply a suitable adhesive to the surface of lthis coil 'afterthe formation thereof. Some time is required for'this adhesive to setand the adhesive has'somewhat of a tendency to contractas it dries.Furthermore the wire itself is'stretched 1 during the formation ofthecoiland tendsto return to its original shape,thus tending to distortthe coil. It is usually impractical to maintain plying a jfilm of liquidadhesive to the surface of v 'a wireas the wire is used. As the wire isremoved from the spool it is directed through a chamber filled withadhesive, thereby coating all f surfaces of the wire with the adhesive.As the wire travels from the adhesive chamber; it passes through anaperture slightly larger-in diameter partment through which wire may bedrawn.

The apertures are so small in size that the adhesive will not run orflow from the adhesive compartment even though the apertures aresubstantially below the adhesive level in the com- In preferred form Iemploy hypothe coil on the mandrel until the adhesivehas dried due tothe time element involved. Asf-a result the moist adhesive,- theresilience of; the

:, wire, and the movement of the mandrel tend to distort the coil as itis removed from the'gmandrel.

"Furthermore the handling of the coilwhilesupported only by'its thinpaper sleeve-tends todistort the coil betweenthe time it is formed andthe time it is attached to the diaphragm. :Ifthe coil is out of round itdoes not properly fit-between the pole piece and the speaker pot unlessan unusuallywide gap is provided, thus impeding the efiiciency of thespeaker. .Ly

It is an important feature of the presentginvention to form the coil ona-m'andreland to hold the coil thereuponuntil the adhesive is entirelydry. The coil is formedabout the paper sleeve after the-attachment ofthis sleeve to the diaphragm and the sleeve is held in cylindrical forml by-the mandrel about which; it is wrapped during a large part of thespeaker assembly operation. Beforethe diaphragmand coil-areremoved fromthe supporting mandrel the adhesive is completely dried by infra redlamps or other suitable means, thus insuring the proper shape of thecoil and minimizing the handling thereof before the speaker iscompletely assembled.

An added feature of the present invention resides in the provision of ameans for reversing the direction of wind of the wire so that a coil oftwo thicknesses of wire is provided. The paper sleeve which forms thecore is so formed as to be thicker on one end than on the other. Thewire is wrapped about this sleeve or the portion thereof of lesserthickness. When the wire reaches the end of the coil, means is providedfor reversing the direction of the wire so as to provide a layer of wireoverlying the innermost layer.

An added feature of the present invention lies in the provision of amandrel on which thespeaker may be assembled to insure the properrelationship of the parts and'to prevent fracturing of the diaphragmduring the assembling operation. This mandrel is designed to support thediaphragm so that the paper sleeve can be attached thereto at the centerthereof. The coil is next wound about the sleeve so that the coil isproperly positioned at the center of the diaphragm. Means is providednear the periphery of the mandrel and externally of the diaphragm forholding the ends of the wire coil to insure the drying of the adhesive.The mandrel may also be used to hold the diaphragm while the ends of thecoil are anchored and soldered to suitable leads.

These and other objects and novel features of the present'invention willbe more clearly and fully set forth in the following specification andthe adhesive chamber showing the manner in which the adhesive is appliedto the wire as it passes through the chamber.

I Figure 4 is a sectional view through the speaker diaphragm at thebeginning of the assembly operation.

Figure 5 is a diagrammatic view of a paper strip which may be used toform the core of the coil'attached to the diaphragm.

Figure 6 is a side elevation view of the speaker diaphragm with thepaper coil, core and coil attached thereto.

Figure 7 is an enlarged view showing the mandrel on which the diaphragmis mounted during the formation of the coil thereupon.

Figure 8 is a front elevational view of the diaphragm and mandrel at thecompletion of the coil winding operation.

Figure 9 is a view similar to Figure 8 showing (ill the manner in whichthe ends of the coil are,

anchored to suitable leads or conductors.

Figure 10 is a view similar to Figure 9 showmg the completion of thecoil forming operation,

Figure 2 of the drawings. In this figure is i1- lustrated a supportingstandard l0 mounted upon a base or table H and including a pair ofspaced uprights [2 connected at their upper extremity by a cross memberl3. A pair of arms M are supported in any suitable manner by the crossmember [3 to rotatably support a spool IS. A substantially V-shapedbrace [6 having a roll er I! at its lower extremity acts as a guide forthe wire l9 in its movement from the spool 15 to winding position.

The coil winding apparatus also includes a shaft or spindle 20 mountedon spaced supports such as 2| and provided with an operating pulley 22on one end thereof. The pulley 22 is driven by a belt 23 extending overa suitable pulley 24 on the drive shaft of a motor 25. When the motor 25is in operation the belt 23 acts to rotate the shaft or spindle 29. v

An upright 26 is provided adjacent the support 2| which upright supportsa rearwardly extending shaft or pivot 21. An adhesive conductor 29 isprovided with a pair of upwardly extending brackets 30 which pivotallyengage about the shaft 21. A filling opening 3| is provided at the topof the conductor 29 and a tubular sleeve 32 extends downwardly from theconductor 29 and is closed at its lower extremity by a plug 33 having aguide arm 34 integral therewith.

The tubular-member 32 is provided with a pair of aligned opposedapertures 35 and 38 therein which are tapped to receive the externallythreaded end of a suitable hypodermic needle fitting 31 or 39. Thefittings 3'! and 39 respectively support the hollow hypodermic needles40 and M which extend in aligned opposed relation in opposite directionsfrom the tubular member 32. l

The hypodermic needles 40 and M are of proper internal diameter toreceive the wire 19 and to allow the wire to pass freely therethrough.At least the needle 40 is of sufficient internal diameter to permit thewire to be carried from the adhesive chamber 42 within the tubularmember 32 without scraping all of the adhesive from the surface of thewire.

It will be seen that as the wire 19 is drawn from the spool I5 itiscarried through the adhesive chamber 42 and coated on all surfaces withliquid adhesive. The wire l9 then passes through the needle 40 wherejust sufficient adhesive remains on the wire to properly adhere the wireto the coil and in coiled formation.

The uniform coating of adhesive is not sufficient to greatly increasethe diameter of the coil and all of the coils are of similar diameter inview of the even coating of adhesive on the wire.

-Either or both of the needle fittings 31 and 39 may be removed beforethe start of the coating operation so that the wire [9 may be threadedtherethrough without difficulty. In usual practice the wire I9 isthreaded through the needle 41 and through the opposed aperture 35 inthe tubular member 32-while the needle fitting 31 is removed. The wireis then inserted through the hypodermic needle 40 from the inner endthereof, thus providing a continuous path for the wire through the bodyof adhesiv In the formation of speaker units the diaphragm 43, bestillustrated in-Figure 4 of the drawings, is mounted upon a mandrel 44illustrated in Figure 7 of the drawings. The diaphragm 43 usuallyincludes a central flange'45 which is centered in respect to a circularperipheral flange 46. The body of the diaphragm 43 is generally coneshaped between the flange 45 and the flange 46 comprising a tapered body41 having a series of circular corrugations 49 extending thereaboutbetween the cone-shaped body 41 and the flange 46. Additional steps maybe provided if desired in the cone shaped body to render the coneproperly flexible to produce the desired sound.

A paper sleeve or tab is secured to the diaphragm 43. This sleeve isformed of a paper strip 50best illustrated in Figure 5 of the drawings/The strip is of proper length to form a sleeve of two laminationsthroughout half its length, and of a single thickness throughout theremainder of its length. The portion 5| of the strip forms the innerlamination and the portion 52 forms an outer lamination throughout partof the length of the sleeve. The double thickness or reinforced end ofthe sleeve 50 is secured to the diaphragm, with the single thicknessportion on the free end of the sleeve to support the wire coil.

In attaching the paper core or sleeve 50 to the diaphragm 43, the papersleeve is wrapped about the projecting shank 53 of the mandrel 44. Afterthe sleeve is in place on the shank 53, the diaphragm 43 is insertedover the sleeve to hold the sleeve in coiled relation. Adhesive isapplied at 54 at the juncture between the paper sleeve and the flange 45of the diaphragm. This is usually accomplished by wrapping the paperabout the shank 53 during rotation of the shank, inserting the diaphragm43 in place, forcing adhesive by an suitable means at the juncture ofthe sleeve and diaphragm during rotation thereof. The sleeve is thusattached to the diaphragm and the coil is in readiness to be formed. Thewire I9 is then anchored in a coil spring 55 mounted near the peripheryof the flange 56 at the outer margin of the mandrel 44. The wire isdrawn adjacent the shoulder 51 formed between the single thicknessportion of the sleeve 50 and the double thickness portion thereof andthe mandrel 44 is rotated to wind the wire I9 about the single thicknessportion of the sleeve 50.

Prior to the coil winding operation a coil limiting sleeve 59 is engagedon the end of the shank 53. The sleeve 59 is provided with a peripheralflange 60 by means of which the sleeve may be rotated, an internallythreaded portion 6| to engage on the externally threaded portion 62 ofthe shank 53, and a projecting sleeve portion 63 which is undercut toengage over the end of the sleeve 50. This projecting sleeve portion 63limits the length of the coil. As a result when the wire I9 has beenwound about the single thickness portion of the sleeve 50 until the wireengages the projecting sleeve portion 53, the wire will build up on thefirst layer nd start a reverse winding overlying the first windingmentioned. This reverse winding is continued until the wire reaches thedouble thickness portion of the sleeve 50 whereupon rotation of themandrel 44 is stopped, the coil wire broken off at a point spaced fromthe core and the end. of the wire limitin sleeve forms a shoulder whichwill automatically terminate the inner coil layer and start.

It is onl necessary four the second coil layer.

the operator to guide the wire during the coilingj '"tion of the papercore.

operation and to stop the rotation when the second coil layer reachesthe double thickness por- As a result the task of "forming the coil onthe diaphragm is greatly simplified and the speed of operation isgreatly increased. Furthermore, the coil may be properly wound by arelatively unskilled worker. In

' Lead wires or conductors I0 and II are likewise inserted into theeyelets 66 and a drop of solder or similar material is placed upon eacheyelet to electrically connect the coil ends 61 and 69 to the lead wiresI0 and II and to anchorthe ends of the coil. The lead wireslli and. 1|are connected in the proper circuit so as to produce electrical impulsesthrough the wire coil I9. .As

, soon as the lead wires have been properly attached a spider of fabricor the like, indicated by the numeral I2, is inserted over the sleeve 50and coiled to encircle the joint between the paper core and thediaphragm 43. Adhesive is applied about the inner periphery of thefabric spider I2 to adhere this member to the diaphragm 43.

During the preceding process, the tab or sleeve 50, the diaphragm 43,the voice coil, the coil leads, and the spider are applied in sequence.In volume assembly, the various steps are followed by diflerent workers,so that the adhesive holding the coil tab or sleeve to the diaphragm andthe adhesive on the coil wire have some time to set before the spider isapplied. In order to insure proper drying of the adhesive, infra-redheat bulbs are directed toward the assembly at one or more points duringor after the process described. When the adhesive has set, the assemblyis removed from the mandrel 44, the empty mandrels returnedto the firststage of the assembly process, and the diaphragm voice coil assemblymounted in the speaker basket.

The peripheral flange I4 of the speaker basket I6 supports the rim 46 ofthe diaphragm 43. A gasket I5 overlies the diaphragm rim, and theseelements are adhered together. The remaining assembly process isgenerally conventional. A pad I3 of felt or the like is adhered to thecenter of the diaphragm to close the end ofthe coil sleeve 59. Thespider I2 is adhered to the speaker basket I6 at 85 to seal the voicecoil from dust and dirt. The speaker coil extends into the gap 82between the pole piece 8| of the magnet and the speaker pot I9. The coilleads III and II are connected to spaced terminals 81 projecting fromthe speaker basket.

A shoulder 84 on the pole piece is sealed with respect to the speakerpot I9 by a resilient washer 83. This washer, the pad I3, and the spider12 completely seal the coil when it is in the gap 82. The mountingbracket 86 and insulation plate 89 are additional accessories.

The advantage of the present method of forming speakers lies in thesimplicity thereof, the speed with which the speakers may be assembled,and the quality of the voice coils formed. The diaphragms are formed ofmolded pulp or similar material and are ready for use as supplied. The

rpen nst i 2 :ienmin th sl e ,d i

:by, the same nu1 nera1 (are ,stamped out of paper :the mandrel .44.during the. entire assembly opera- .tion, the. coilsnare prevented,from distorting as theadhesiverdries.

;.In accordance, withthe I patent statutes, I have described theprinciples of construction and op- ,eration .of my apparatus, for makingradio :speakers, ,and while ,I have endeavored to set .forth-the best.embodiment thereof,.I desire to have itunde'rstood that obviouschangesmay be i rnade .within the scopepf the following claims e-withoutdeparting from theispirit of my inven- 1.-The method, of connecting acoil to adiaphragm through the use of ajrotatable mandrel,

diaphragm rover: theshoulder, attaching the dia- ;;phragm to theshoulder appl'ying adhesive to a wire,. and wrapping ,said ,wire. aboutthe sleeve without removing said sleeve from it the mandrel to formacoil on saidsleeve.

;8 2. The method ,describedin claimlin which .said flexible material isa strip or paper and said shoulder isformed by wrapping more turns ofsaidpaperadjacent said one end.

BARTON T. "SETCHELL.

- REFERENCES CITED The following-references are of record inethe file ofthis patent:

UNITED STATES PATENTS Number Name Date 247,082 Manly et a1. Sept. 13,1881 366,408 Lange July 12, 1887 862,935 Pfanstiehl Aug. 13, 19071,848,433 Pridham Mar.'8, 1932 1,891,404 Engholm Dec.120, 1932 1,923,924Engholm Aug. 22, 1933 1,935,404 Leopold Nov. 14, 1933 1,936,918 SeabertNov. 28, 1933 1,956,826 Engholm May 1,1934

, 1, 960,016 Knauf, Jr May 22, 1934 1,994,534 Robinson Mar. 19, 19352,207,240 Cornwall July9, 1940 2,207,487 Kirkpatrick July 9, 19402,359,249 Scheer Sept.'26, 1944 2,435,093 Mitschrich Jan.127, 19482,538,621 Hopkins Jan. 16, 1951

